Relationship of Potassium and Sodium Content to the Composition of Pigs

Abstract

The chemical composition of 24 pigs ranging in live weight from 181–220 lb. was determined. The animals were divided into seven compartments at slaughter. These included the carcass, hair, head, blood, viscera, empty G.I. tract and the G.I. contents. These components were frozen, sliced on a bandsaw, ground until homogeneous and sampled and analyzed for water, protein, ether-extract and ash. The samples were also used for potassium and sodium analyses by flame photometry. The empty bodies of the pigs contained on average 0.20% potassium (177 gm.) and their carcasses contained 0.21% (144 gm.). When expressed on a fat-free basis, these figures were increased to 0.30% and 0.34% potassium, respectively. The sodium content of the empty bodies was 0.083% and for the carcasses 0.072%. All correlations between the gross chemical composition of the carcasses and either the potassium content of the empty bodies or the carcasses were significant. Similarly, all correlations between the gross chemical composition of the empty bodies or entire bodies and their potassium content were significant. The magnitude of the standard errors from the resulting regression equations suggests that potassium is of questionable value for predicting the chemical composition of pig bodies or carcasses, unless methods are found for reducing some of the errors in these relationships. These errors include any inaccuracies in the measurement of the potassium content as well as those in determining the gross chemical composition of the pig. Percent sodium was less closely related to the composition of the pigs than was potassium. It was shown that sodium was more closely related to the composition of the bodies than of the carcasses. The inclusion of both sodium and potassium in a multiple regression equation increased the accuracy of prediction over potassium alone. These results are discussed in relation to the non-destructive estimation of the composition of live pigs.